Is it really the Transplant Renaissance in CML Acceleration Phase

Abstract

WHO 2016 guidelines regarding chronic myeloid leukemia (CML) do not contain groundbreaking changes [1]. Mainly criteria of acceleration phase (AP) identification were revised. Despite these changes, the guidelines are still not standardized and differ significantly, even when compared to guidelines of European Leukemia Net (ELN) [2], International Bone Marrow Transplant Registry (IBMTR) or M. D. Anderson Cancer Center, to give some examples (Table 1). Compared to previous editions of the WHO classification, new parameters appeared, the presence of which requires identification of acceleration phase. In this case, one should list e.g. chronic leukocytosis (>10 × 109/L), non-responding to treatment, chronic splenomegaly non-responding to treatment, additional clonal chromosomal aberrations (the so-called "major route") in Ph+ cells on diagnosis. New provisional criteria also appeared, related to response to therapy using tyrosine kinase inhibitors (TKI). Among the latter ones the following were distinguished: hematological TKI resistance when used as a first-line or lack of complete hematological response (CHR) during first-line treatment when using TKI; hematological, cytogenetic or molecular resistance during treatment with a subsequent second TKI; presence of two or more mutations within BCR/ABL during TKI therapy. These changes resulted in necessity to diagnose acceleration phase much more frequently, compared to e.g. ELN criteria. This presents importance, particularly for patients already treated with TKI, as it increases the percentage of patients with indications for allogenic hematopoietic stem cell transplantation (allo-HSCT). It contrasts with everyday practice and tendency to marginalize the role of transplanting hematopoietic cells in case of this disease classification unit, in the TKI era. The thesis as such is best illustrated with an example.